In many circumstances, it is desired to provide a gate to enable access of persons in one direction, i.e. from a first area to a second area, while preventing or at least detecting circulation in the opposite direction. Such control is required for example to enable people to freely enter a store through certain portals while exit is only permitted through other portals.
Turnstiles are often used for such a purpose, but they present important limitations since they do not provide detection of a person jumping across the gate to exit, they present a serious hindrance to the passage of handicapped persons and shopping carts, and they are not adapted to enable free circulation in the opposite direction to let people freely exit the controlled area in case of emergency such as in the event of a fire alert. Similarly, gates comprising two or more sequential interlocked arms, wherein the first arm must be opened to unlock the second arm, may also be fooled by having a person keeping the first arm open thus enabling other persons to exit.
A number of more sophisticated gates and barriers have been provided in the prior art in attempt to overcome the above limitations and drawbacks, most of them relying on a simple motor driven pivotal arm and different sensing devices to manage arm operation in connection with people detection to allow one-way or two-way circulation of incoming persons while preventing arm/people interferences. This prior art solution discloses a passage barrier comprising a swiveling barrier and at least one sensor technology located in the sidewalls along the passageway and emitting a detection wave to detect the presence of a person in the swiveling area and/or the swiveling angle of the barrier. The prior art further teaches that multiple sensors may be used to determine the position and direction of movement of the person and that the barrier is at least partly made of detection wave transparent material.
However, it is well known that this type of system based on a motor driven barrier automatically opening when presence of an incoming person is detected presents a poor performance for preventing persons from exiting through the barrier when it is open to let other persons enter. While gates according to this concept keep the barrier arm locked in a closed position as long as no person has been detected at the entry end, they suffer from the same limitation as the interlocked arms when presence is detected at the entry end. Furthermore, in addition to presenting a risk of hurting a person in case of misdetection; this type of motor driven barriers moving slowly for safety concerns limits the circulation flow speed. In spite of the number of sensors that can be used according to concepts of the prior art, no indication is disclosed as to the method of controlling the barrier as a function of the signals provided by these sensors, especially in the case of multiple discontinuous detections along the passageway, momentary detections, etc.
It would therefore be a significant advance in the art of gate systems to provide a gate and method enabling accurate detection and tracking of the flow of individual detectable items, such as persons, animals or objects, passing through a gate system and taking appropriate actions without the need for a motor driven barrier arm, thereby providing accurate flow control as a turnstile, without the associated drawbacks.
Therefore, there is a need to provide a flow control gate and associated advanced method to obviate the limitations and drawbacks of the prior art.